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Timing belt disaster - Simple question... maybe.


englishjim
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I am going crazy here, so thanks for any advice:

 

OK...

 

my harmonic balancer/crank pulley has no TDC mark, the key seems to be about 15 degrees off pointing to the passenger side at what I think is TDC - I measured TDC by aligning the cam marks and checking that No. 1 was as high as possible. The problem is the cams might be off (actually I am sure they are off by 1 tooth)

 

Please help!

Jim

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Pull the #1 plug, insert a wood dowel or something else and rotate the engine until the rotor points to the #1 spark plug cap position and the dowel is at the top of the poston stroke. Ignore the cams if they might be off and make sure the dowel doesn't catch or bind. There should be a better description of this in the Garage/How To section in a 'How to change your timing belt thread'. Holler again if you can't find it or need more info.

 

B

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Thanks precise 1. Been on the thread and it seems to assume that you are starting from the right place. Everything is out of whack on my pathy. I have just been sticking a dowel into no1 and I m just off by at least 1 tooth. My aim is to count the 40 teeth between cams and 43 to mark on the crank gear - If its all balanced will that be ok? I will try again in the morning. My brain cant take this. Cheerio!

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You may have to take the timing belt cover off for this one and re-do the timing belt. I think you can get away with just removing the upper timing belt cover though. Take the distributor cap off and make sure the rotor points to the number 1 plug. Count the teeth between the marks on the cam sprockets. If all is well then there should be 40 teeth between the two cam sprocket punchmarks. If you remove the entire cover, there should be 43 between the crank and cam sprocket on the driver side. The pulley is separate from the balancer so there is 6 different ways to put it on. At TDC it should point to the first mark if properly installed.

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I found the problem, the timing belt is the wrong size. Side by side with the original its about 1/4 inch too big. A good warning to cheapskates, its driven me crazy for two days. Very relieved.

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The timing belt is one of the items I get from the dealership, it's not much more and gives me some peas of mind.

 

1993 is when they switched from the square tooth to the round tooth design. Will you share the production date of your pathy and which type of belt it has?

 

B

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I'm with Precise1 on that, timing belts should be bought only from Nissan. I did however replace my last one with a Gates belt and it had the same amount of teeth as there was on the Nissan one. I counted all the teeth to make sure that the belt was the same.

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  • 2 years later...

Could I revive this thread I'm doing mine and I'm a little nervous, are you guys talking teeth on the belt or teeth on the sprockets?

Also do I need to worry about it if the belt didn't break?

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teeth on the belt are what get counted. As far as worrying, anytime you remove the belt, you should be concerned. There is most likely load on one of the cams and it may try to rotate on you. My suggestion would be to take the new belt and, if it has alignment lines, figure out the orientation, then put a mark on the cams and crank where the lines are, making sure the right (non-tensioner) side is taunt. If done carefully, this will prevent you from needing to set TDC before installation.

 

Alternatively, remove the covers and rotate the entire system by hand until the marks on the cams align with the dimples on the back cover, check the mark on the crank and try not to move anything when you pull the old belt

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^Exactly.

It should be easier to to replace an old belt rather than a broken one because the alignment should be there, but do not assume! Verify everything and at most you should have to rock a cam a little.

 

There is a good write up in the Garage/How To section with some pictures and a whole lot of dialogue as well.

 

BTW, no problem reviving old threads about the same thing, that is why they are there... ;)

 

B

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Thanks for the quick and friendly replies, but I did already take the belt off because of the water pump and the only mark I made is one on the belt and one on the right side cam sprocket, what do you mean by "rock a sprocket" and how would you guys recommend I turn the engine if I already have the belt off, should I put it back on and try to get the marks to align?

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I would put the belt back on and count the teeth to any arbitrary points and then rotate the engine until it's at top dead center on the compression stroke and then pull the belt and put it back on with the marks aligned properly so you can be sure you aren't off anywhere.

 

As long as you haven't rotated the crank or the cams individually with the belt of, you shouldn't have any issues doing this.

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Tensioner is off too btw :/ hope that didn't mess anything up. Any suggestions on that as well?

best suggestion here is don't break the damned thing while putting it back in. Drilling out that bolt is a PAIN IN THE ASS!

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Ok let me clarify this one more time please. Since it didn't break and I still have alignment since it ran when I took it apart & assuming the cam didn't rotate from a load on it (didn't from what I seen).

 

All that considered is there any need for me to line up the notches on the sprockets or find TDC? Also are the teeth in between gonna be the only way to tell me if the tensioner is tight enoigh?

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I would put the belt back on and count the teeth to any arbitrary points and then rotate the engine until it's at top dead center on the compression stroke and then pull the belt and put it back on with the marks aligned properly so you can be sure you aren't off anywhere.

 

As long as you haven't rotated the crank or the cams individually with the belt of, you shouldn't have any issues doing this.

This is kind of where I get confused if I haven't rotated the crank I should have to do any of this right?1
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Thanks for the quick and friendly replies, but I did already take the belt off because of the water pump and the only mark I made is one on the belt and one on the right side cam sprocket, what do you mean by "rock a sprocket" and how would you guys recommend I turn the engine if I already have the belt off, should I put it back on and try to get the marks to align?

See Below

 

Ok let me clarify this one more time please. Since it didn't break and I still have alignment since it ran when I took it apart & assuming the cam didn't rotate from a load on it (didn't from what I seen).

 

All that considered is there any need for me to line up the notches on the sprockets or find TDC? Also are the teeth in between gonna be the only way to tell me if the tensioner is tight enoigh?

That is what I meant by maybe having to rock a sprocket, to make sure it lines up properly if it shifted slightly when the belt was removed.

You should always count the teeth between the gears, it is the basic double check that nothing is off.

 

If you did not make marks on the old belt (and corresponding marks on the pulleys) then it is hard to tell if anything has moved, The safe way is to find TDC, align the cams to the marks, verify the crank mark, install the belt and count the teeth.

 

The thread I mentioned before that is in the Garage/How To section was written by a mechanic and does have all this information, including belt tensioning. Did you not take a look? :scratchhead:

 

B

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This is kind of where I get confused if I haven't rotated the crank I should have to do any of this right?1

you shouldn't have to, but I really would if it were me. It will only add another 30 minutes to the over all job. I would say it's worth the peace of mind, and definitely check over that thread on the timing belt how to.

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Yeah I read it I just like to ask questions my own way, I always have a "what about this" type of thing goin on in my head.

I think I'm gonna put the old belt back on how many time do you guys suppose I have to rotate the engine to make them line up?

Also what would I Use to rotate the engine? I have the vibration damper off so I can't really turn it with that nut, should I put it back on?

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Just stick the crank bolt back in the crank. The force it takes to spin the engine doesn't torque down the bolt very tight and it will be easy to take out again, once the marks are lined up.

 

Well, considering it's a 4 stroke engine; the crank spins twice for every rotation of the cams. So you should have it lined up in under two full revolutions of the crank. It won't take long, very easy to do. I've found that there often isn't a mark on the oil pump for the lower timing mark that's supposed to be located parallel to the mark on the crank sprocket, so I will use an automatic center punch to make my own mark (once the cam sprockets are both lined up). This is just for another reference point.

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Just stick the crank bolt back in the crank. The force it takes to spin the engine doesn't torque down the bolt very tight and it will be easy to take out again, once the marks are lined up.

 

 

 

Well, considering it's a 4 stroke engine; the crank spins twice for every rotation of the cams. So you should have it lined up in under two full revolutions of the crank. It won't take long, very easy to do. I've found that there often isn't a mark on the oil pump for the lower timing mark that's supposed to be located parallel to the mark on the crank sprocket, so I will use an automatic center punch to make my own mark (once the cam sprockets are both lined up). This is just for another reference point.

It's actually a v6 but I get the point, I'm pretty sure I'm gonna do this to save myself from taking everything apart again if it doesn't like up,

One last thing, if there was a load on one of the cams and it shifted, I just move it back and everything will be in alignment again?

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ummm... yes, it's a 4-stroke V6 ;)

 

if there is any chance that anything moved, I would start from TDC. You don't want to get it back together and find that it runs like crap cause the belt is a tooth off.

 

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ummm... yes, it's a 4-stroke V6 ;)

 

if there is any chance that anything moved, I would start from TDC. You don't want to get it back together and find that it runs like crap cause the belt is a tooth off.

 

Hahaha sorry, so as long as the notches line up I'm at TDC right?

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